Views are independent of domains. i.e. a view is not part of a domain and may have members from different domains. You can of course create views that use  A Domain filter term  to list only features that are member of a specific domain, but that is only an option and not a must.

However it might be beneficial in some situations to associate specific views with a domain for display purposes. I.e. the client showing domains and views might show only views associated with a specific domain. Therefore the Application Server supports storing associations between views and domains.

A view is associated with a domain if it is either directly associated with that domain or if the view is set to be associated with all domains.